Considerable attention in recent years has been paid to the effects of fat in the diet on health. In particular, interest has become focused on the various types of fats which comprise the fat component of the diet, and the health effects which they have.
Keys et al., Lancet, 2, 959-66 (1957) discloses that saturated fats in the diet cause a rise in serum cholesterol, which in turn has been associated with increased risk of atherosclerosis and heart disease.
Hopkins et al., JNCI, 66, 517-21 (1971) discloses that high linoleic oils (e.g. corn oil) at high levels in the diet can result in increased tumor incidence and tumor size in experimental animals.
Carroll and Broden, Nutrition and Cancer, 6, 254-59 (1985) discloses that high linoleic acid content in dietary fat and oils promotes mammary carcinogenesis in experimental animals.
Mattson and Grundy, J. Lip. Res., 26, 194 (1985), Grundy, New Eng. J. Med., 314, 745 (1986) and Mensink and Katan, Lancet, p. 122 (Jan. 17, 1987) disclose that a diet high in oleic acid and low in saturated fatty acids can reduce low density lipoprotein (LDL) cholesterol, while conserving more high density lipoprotein (HDL) cholesterol than is found in the case of high linoleic acid diet. This may be desirable from the standpoint of reducing risk of heart disease.
Holman, Prog. Chem. Fats & Other Lipids, 9, 279 (1971) at p. 382 notes that a .alpha.-linolenic acid can function as an essential fatty acid in that it promotes growth almost as well as linoleic acid. Neuringer et al, J. Clin. Invest. 73, 272 (1984) reports that .alpha.-linolenic acid in the diet improved the visual acuity of young growing monkeys, by acting as a precursor to docosahexaenoic acid, a component of photoreceptor membranes. Recent work by Renaud et al., Am. J. Clin. Nutr., 43, 136 (1986) associates increased dietary .alpha.-linolenic acid in human subjects with reduced platelet aggregation (suggesting possible reduced risk of thrombosis). Berry and Hirsch, Am. J. Clin. Nutr., 44, 336 (1986) associated increased .alpha.-linolenic acid in human adipose tissue (hence, increased dietary .alpha.-linolenic acid) with decreased blood pressure.
U.S. Pat. No. 4,277,412, Logan, issued July 7, 1981 discloses a process for separating glyceride oils by degree of unsaturation, using a solid adsorbent. The process involves contacting an organic solvent solution of the oil with a permutite adsorbent which selectively adsorbs the unsaturates, and then desorbing the unsaturates from the permutite adsorbent and evaporating the solvent. In Example 3 of the patent, sunflower oil is treated according to the process. The resulting unsaturate-enriched oil fraction contains (analyzed as Me esters) 0.54% saturated fatty acids, 21.13% oleic acid and 78.33% linoleic acid. The oil is stated to be useful as a salad or cooking oil.
U.S. Pat. No. 4,297,292, Logan et al., issued Oct. 27, 1981 discloses a process for separation of triglyceride oils by degree of unsaturation on a cation exchange resin. Tables VI and VII in the patent disclose separations of a mixture of tristearin, triolein and trilinolein. In Example IV of Table VI an oil consisting of 88% triolein and 12% trilinolein is produced. In Example D of Table VII an oil consisting of 3% tristearin, 91% triolein and 6% trilinolein is produced.